HARLEY DAVIDSON CAMPAIGN NO 650.MFG.BETWEEN JAN.1, 1973 & JAN.29, 1973.POSSIBILITY THAT IN CHANGING THE LIGHTING TO MEET FEDERAL MOTOR VEHICLE SAFETYSTANDARD 108, A DESIGN ERROR WAS MADE IN THE TAIL LIGHT WIRING.THIS ERRORALLOWED THE WIRE TO CONTACT THE REAR WHEEL WHEN THE LIGHT WAS ADJUSTED TO THEREAR POSITION.(CORRECT BY INSPECTING AND PLACING A CLIP TO HOLD WIRE INPROPER POSITION.